Another way to see the changing nature of the American death penalty: The gradual decline of death row populations. At the death penalty’s modern peak around the turn of the century, death rows housed more than 3,500 inmates. That number is falling, and it has been falling for some time. New Justice Department data show that death-row populations shrank in 2015, marking the 15th consecutive year with a decline.

There were 2,881 inmates on state and federal death rows in 2015, the last year for which the Justice Department has nationwide data available. That was down 61 from the year before.

States carried out 28 death penalties in 2015, but nearly three times as many inmates — 82 — were removed from death rows “by means other than execution,” the Justice Department’s report states. (Another 49 inmates arrived on death row in 2015.)

In some cases, inmates left death row after being cleared of the crimes for which they were sentenced. Five people sentenced to death were exonerated in 2015, according to the National Registry of Exonerations, a project of the University of Michigan Law School and the Northwestern University School of Law.

Other inmates died of other causes before their executions could occur. In Alabama, three inmates died of natural causes in 2015 and a fourth hanged himself that year inside a prison infirmary, according to corrections officials and local media reports. North Carolina officials say one death-row inmate died of natural causes that year, another was resentenced to life without parole and a third had his death sentence vacated and a new trial ordered.

A 2014 photo showing the gurney in the execution chamber at the Oklahoma State Penitentiary in McAlester, Okla. (Sue Ogrocki/Associated Press)

Death sentences were thrown out in some cases. Four death-row inmates in Maryland had their sentences commuted to life in prison without parole in 2015, a decision made by then-Gov. Martin O’Malley after that state formally abolished the death penalty.

As death-row populations have been shrinking for years, state and federal prisons overall have seen a more recent decline. According to the Justice Department, 1.53 million people were held in such facilities at the end of 2015, a decrease of 35,500 people from the year before.

Another shift also has occurred: The number of people sentenced to life in prison has ballooned, reaching an all-time high last year, according to a report released this week from the Sentencing Project. The report states that more than 161,000 people were serving life sentences last year, with another 44,000 people serving what are called “virtual life sentences,” defined as long-term imprisonment effectively extending through the end of a person’s life. Similar to overall prison populations, people of color are disproportionately represented; black people account for nearly half of the life or virtual-life sentences tallied in the report.

The declining use of the death penalty also leaves unanswered how many of the men and women facing the death penalty will ever enter an execution chamber. The time between a death sentence being handed down and carried out has grown significantly. In 2001, when the American death penalty was at its apex with 3,500 prisoners on death row, they were spending an average of 8.6 years there after receiving their sentence, according to federal data. By 2013, the last year for which full Justice Department data are available, the death-row population fell below 3,000 while their time there ballooned to an average of 14.6 years.

When the U.S. Supreme Court upheld Oklahoma’s lethal-injection procedure in 2015, Justice Stephen G. Breyer, joined by Justice Ruth Bader Ginsburg, dissented and questioned whether the death penalty is constitutional. In that dissent, Breyer noted the extended periods that elapse before death-row inmates are executed, adding that the time can be even longer for those death penalties actually carried out; for inmates executed in 2014, an average of almost 18 years elapsed between sentence and punishment, he wrote.

“A death penalty system that seeks procedural fairness and reliability brings with it delays that severely aggravate the cruelty of capital punishment and significantly undermine the rationale for imposing a sentence of death in the first place,” Breyer wrote.

In response, the late Justice Antonin Scalia blamed the extended delays on “the proliferation of labyrinthine restrictions on capital punishment” that he said stemmed from the Supreme Court’s own rulings. Scalia wrote that Breyer’s “invocation of the resultant delay as grounds for abolishing the death penalty calls to mind the man sentenced to death for killing his parents, who pleads for mercy on the ground that he is an orphan.”

Breyer revisited his dissent last month while Arkansas was seeking to carry out its first execution since 2005. An inmate named Ledell Lee, 51, was sentenced to die for the killing of Debra Reese, who was beaten to death in her home in 1993. Lee, who had long denied any involvement in her death, sought DNA testing to prove his innocence. His attorneys appealed to the U.S. Supreme Court for a stay, but in a 5-4 decision, the justices sided with the state and denied the request.

Dissenting from that decision, Breyer questioned Arkansas and its schedule of executions.

“Why now?” he wrote. “The apparent reason has nothing to do with the heinousness of their crimes or with the presence (or absence) of mitigating behavior. It has nothing to do with their mental state. It has nothing to do with the need for speedy punishment. Four have been on death row for over 20 years. All have been housed in solitary confinement for at least 10 years. Apparently the reason the state decided to proceed with these eight executions is that the ‘use by’ date of the state’s execution drug is about to expire.”

Lee was executed that night, becoming the first of four inmates put to death in Arkansas in a span of eight days. Courts blocked the other four executions that had been planned. According to the state, one of the three drugs used in lethal injections there expired on Sunday, and due to the ongoing shortage, officials have said they are unclear when more can be obtained. Arkansas currently has no other executions scheduled.

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